I would think if/when you can get her fixed she will settle. I have numerous cats who are indoor only and have no issues.
I'm not so sure about this "false heat" thing. It's normally something that happens after being spayed, not before. Any heat of any kind, even so soon after having kittens, will result in another litter if the cat is allowed to mate. A few years back when I had unspayed ferals around they would routinely be pregnant again a few weeks after having one litter.
Nothing false about that.
Reg is completely correct in saying there aren't many farmers who would take on more cats. Most farmers have more than they want in the first place and, if the coyotes, cars, farm machinery, livestock, etc. don't get them then the farmer will. I have been told of special buckets filled with water with lids on kept for that purpose. Farmers who fix the cats under their care and look after them properly are few and far between.